To develop photographic products, the exposed product is normally processed with a developer which comprises at least one silver halide developing agent, for example hydroquinone or hydroquinone derivatives. Conventionally, the exposed product is immersed in a developer, and is then immersed in a fixer, then in a washing bath. Over time, the active compounds in the developer are depleted and it thus becomes less efficacious, necessitating the use of a solution for maintaining the activity of the developer (replenisher).
This conventional technique requires large quantities of water and solution to be used. Furthermore, the destruction or recycling of these large volumes of solution leads to numerous problems, in particular in terms of protection of the environment. This problem is all the more significant as standards for disposing of chemical solutions are becoming more and more strict.
In order to reduce the problems related to the use of these conventional developers, the developing agents have been incorporated into one of the layers of the photographic product. Following exposure, these products with incorporated developing agents are developed using a basic solution, called an activator, which contains no developing agent. In general, the exposed photographic product is contacted with the activator in a conventional manner by immersing in a tank containing the activator solution.
FR-2,003,178 and FR-2,414,743, describe methods which consist of contacting the photographic product to be developed with a support, generally gelatin, that is impregnated with basic activator comprising an alkaline metal hydroxide (sodium hydroxide, potassium hydroxide).
In order to limit the problems related to the use of a large volume of solution, this technique would seem advantageous. This technique of development by impregnation considerably limits the volume of processing solution used in development, and consequently all the problems of recovery, recycling or destruction of photographic solutions. However, these techniques necessitate complex additional processing steps, such as, for example, the conditioning of the activator on the layer of gelatin. Additionally, this technique does not give satisfactory sensitometric results, in particular for photographic products intended for the field of graphic arts that must have high contrast.
For many years, films and development processes intended for the graphic arts industry, have been designed to obtain an improved image quality by virtue of high contrast.
It is known to obtain such films with silver halide photographic emulsions containing a majority of silver chloride, and which can be developed with a hydroquinone developer containing a small quantity of sulfite. This type of developer has drawbacks, such as a lack of solution stability.
It is also known to obtain high-contrast films by using hydrazine compounds, either in the photographic film or in the developer. For example, U.S. Pat. No. 4,269,929 describes a method of developing a photographic product for graphic arts, in the presence of a hydrazine compound, with an alkaline developing solution that has a pH above 10 and below 12 and which contains dihydroxybenzene and 3-pyrazolidinone, sulfite as a preservative and an amino compound (or booster) to promote contrast.
Developers comprising hydrazine and amino compounds are known in the prior art for the purpose of increasing the contrast of photographic films destined for the graphic arts industry. Though very promising, this technique exhibits drawbacks because certain amino compounds are toxic, or too volatile. They sometimes have a tendency to form an azeotrope with water or exhibit solubility problems in photographic developers.
It has been attempted to overcome these drawbacks by incorporating the amino compound and/or the hydrazine compound into the photographic product. The properties of these systems are in particular highly dependent on the processing conditions. That is to say, variable sensitometric results are obtained depending upon the pH of the processing solution, the halide concentration of this solution, or the level of agitation of the processing solution.